The present invention relates to a side impact airbag apparatus that protects an occupant seated in a vehicle seat from an impact by deploying and inflating an airbag in the vicinity of a side of the occupant when the impact is applied to the vehicle from the side of the vehicle seat.
Some automobiles are equipped with seats arranged side by side in the width direction. In such an automobile, when an impact is applied to a body side portion due to a side collision, it is important to protect not only the occupant seated in the seat on the side closer to the body side portion that has received the impact (the seat on the impact side), but also the occupant seated in the seat on the side farther from the impact receiving body side portion (the seat on the side opposite to the impact). Side impact airbag apparatuses are effective as means for protecting occupants located on the impact side and on the side opposite to the impact. When an impact is applied to the automobile due to a side collision, the side impact airbag apparatus causes a gas generator to generate inflation gas. The inflation gas deploys and inflates an airbag at a position close to the side of an occupant to reduce the impact. Particularly, a side impact airbag apparatus for protecting an occupant on the side opposite to the impact receives the occupant on the side opposite to the impact. This restrains the occupant on the side opposite to the impact from interfering with the occupant on the impact side or interior parts.
One form of a side impact airbag apparatus for protecting an occupant on the side opposite to the impact includes an airbag and a gas generator arranged in the rear lower portion of the airbag. The airbag, together with the gas generator, is fixed to an automobile seat. At a position close to the side of the upper body of an occupant, including the head, the airbag is deployed and inflated diagonally forward and upward from the fixed position. In this type of side impact airbag apparatus, it is important to deploy the airbag within a predetermined deployment area in a short time to properly protect the occupant.
However, since the airbag is fixed to the automobile seat only at the rear lower portion, the momentum of the diagonally forward and upward deployment and inflation of the airbag cause the airbag to act to fall forward in a rotating manner about the part at which the airbag is fixed to the automobile seat. This may cause the airbag to project forward from the deployment area. Also, after having projected forward, the airbag acts to fall rearward in a rotating manner in reaction, which may cause the airbag to project rearward from the deployment area.
As another form of a side impact airbag apparatus, an apparatus with an airbag having a strap has been proposed (for example, refer to International Publication No. 2001/049535). The front end of the strap is attached to the front end of the airbag, and the rear end of the strap is attached to a part of the airbag that is fixed to an automobile seat or to a part in the vicinity of the fixed part.
In the side impact airbag apparatus disclosed in the above document, the strap is tensioned as the airbag is deployed and inflated and, in turn, applies tensile force to the airbag to restrain the airbag from rotating forward. Accordingly, it is possible to restrain the airbag from falling forward and projecting forward of the deployment area.
However, when the airbag is rotated rearward in reaction, the strap is slackened. The strap therefore cannot restrain the rearward rotation of the airbag. Thus, as in the case without a strap, the airbag acts to fall rearward in a rotating manner. As a result, the airbag may project rearward from the deployment area.
Such problems can occur in a type of side impact airbag apparatus that deploys and inflates an airbag between the body side portion of an automobile and an automobile seat, which is referred to as a near side airbag apparatus.